crypto: talitos - static code checker fixes

crypto: talitos - static code checker fixes

-change req_ctx->nbuf from u64 to unsigned int to silence checker
warnings; this is safe since nbuf value is <= HASH_MAX_BLOCK_SIZE
-remove unused value read from TALITOS_CCPSR; there is no requirement
to read upper 32b before reading lower 32b of a 64b register;
SEC RM mentions: "reads can always be done by byte, word, or dword"
-remove unused return value of sg_to_link_tbl()
-change "len" parameter of map_single_talitos_ptr() and
to_talitos_ptr_len() to unsigned int; later, cpu_to_be16 will __force
downcast the value to unsigned short without any checker warning

Signed-off-by: Horia Geanta <horia.geanta@freescale.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>